1. Field of the Invention
This invention relates to hole formers for use in fabricating concrete and more particularly for forming a hole aligned with a connecting pipe for a manhole invert.
2. Description of the Related Art
Forming holes in concrete manhole walls by use of a hollow cylinder section in a concrete mold is a preferred way of making concrete manholes. However the hollow cylinder sections are difficult to align with the manhole such that the hole left in the manhole wall will be aligned with an internal invert to provide a good pipe connection. If the pipe is not properly aligned with the internal invert, leaks may result. Further, misalignments with the manhole invert may cause damming at the intersection of the invert pipe and the manhole invert, restricting the flow therein.
Prior art hole formers have had bolts around the perimeter of the hole for attaching the hole former to the mold which makes it difficult to install and remove the hole former. Further, the hole formers did not use attachments to make the hole formers universally adaptable to different manhole molds.